The present invention relates in general to infrared (IR) sensing devices, and more particularly to a self-calibrating IR sensing device.
IR sensors are used to measure temperatures of remote objects by detecting the infrared radiation emitted from the target object. In a typical configuration, IR radiation enters the housing in which the sensor element is located through an IR transparent window and impinges upon the sensor. The temperature is typically measured by detecting the IR radiation and determining its effect on a thermally isolated radiation absorbing area of the sensor. In many typical applications the radiation from the remote object is gathered and focussed onto the sensing element by an external mirror arrangement for increased effectiveness. When the surface of the window or the mirror arrangement becomes contaminated by particles or residues that absorb IR radiation, incoming IR radiation is absorbed such that the amount of IR radiation passing through the window becomes attenuated. The IR transmission capability of the window and the IR reflectance capability of the mirror arrangement is therefore degraded by the presence of IR-absorbing contaminants. Such degradation results in erroneous temperature readings by the sensor. Accordingly, what is needed in the art is the ability to easily counter the attenuation effects of IR-absorbing contaminants deposited on the transmission window and mirror arrangement so as to accurately detect and measure the IR radiation received from a target object.